Mu-synthesis PID Control of Full-Car with Parallel Active Link Suspension Under Variable Payload

TL;DR

This paper introduces a combined mu-synthesis PID control scheme for a novel active suspension system, enhancing ride comfort, road holding, and robustness against payload variations through multi-objective control and nonlinear simulations.

Contribution

It develops a novel combined mu-synthesis and PID control approach for PALS, improving performance over traditional H-infinity control under variable payloads.

Findings

Superior ride comfort and road holding compared to conventional control methods

Enhanced robustness to payload variations demonstrated in simulations

Effective multi-objective control for low and high frequency dynamics

Abstract

This paper presents a combined mu-synthesis PID control scheme, employing a frequency separation paradigm, for a recently proposed novel active suspension, the Parallel Active Link Suspension (PALS). The developed mu-synthesis control scheme is superior to the conventional H-infinity control, previously designed for the PALS, in terms of ride comfort and road holding (higher frequency dynamics), with important realistic uncertainties, such as in vehicle payload, taken into account. The developed PID control method is applied to guarantee good chassis attitude control capabilities and minimization of pitch and roll motions (low frequency dynamics). A multi-objective control method, which merges the aforementioned PID and mu-synthesis-based controls is further introduced to achieve simultaneously the low frequency mitigation of attitude motions and the high frequency vibration suppression of the vehicle. A seven-degree-of-freedom Sport Utility Vehicle (SUV) full car model with PALS, is employed in this work to test the synthesized controller by nonlinear simulations with different ISO-defined road events and variable vehicle payload. The results demonstrate the control scheme's significant robustness and performance, as compared to the conventional passive suspension as well as the actively controlled PALS by conventional H-infinity control, achieved for a wide range of vehicle payload considered in the investigation.